368 lines
9.7 KiB
C
368 lines
9.7 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* taskset - retrieve or set a processes' CPU affinity
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* Copyright (c) 2006 Bernhard Reutner-Fischer
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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//config:config TASKSET
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//config: bool "taskset (4.2 kb)"
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//config: default y
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//config: help
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//config: Retrieve or set a processes's CPU affinity.
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//config: This requires sched_{g,s}etaffinity support in your libc.
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//config:
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//config:config FEATURE_TASKSET_FANCY
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//config: bool "Fancy output"
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//config: default y
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//config: depends on TASKSET
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//config: help
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//config: Needed for machines with more than 32-64 CPUs:
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//config: affinity parameter 0xHHHHHHHHHHHHHHHHHHHH can be arbitrarily long
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//config: in this case. Otherwise, it is limited to sizeof(long).
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//config:
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//config:config FEATURE_TASKSET_CPULIST
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//config: bool "CPU list support (-c option)"
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//config: default y
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//config: depends on FEATURE_TASKSET_FANCY
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//config: help
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//config: Add support for taking/printing affinity as CPU list when '-c'
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//config: option is used. For example, it prints '0-3,7' instead of mask '8f'.
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//applet:IF_TASKSET(APPLET_NOEXEC(taskset, taskset, BB_DIR_USR_BIN, BB_SUID_DROP, taskset))
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//kbuild:lib-$(CONFIG_TASKSET) += taskset.o
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//usage:#define taskset_trivial_usage
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//usage: "[-ap] [HEXMASK"IF_FEATURE_TASKSET_CPULIST(" | -c LIST")"] { PID | PROG ARGS }"
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//usage:#define taskset_full_usage "\n\n"
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//usage: "Set or get CPU affinity\n"
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//usage: "\n -p Operate on PID"
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//usage: "\n -a Operate on all threads"
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//usage: "\n -c Affinity is a list, not mask"
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//usage:
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//usage:#define taskset_example_usage
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//usage: "$ taskset 0x7 ./dgemm_test&\n"
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//usage: "$ taskset -p 0x1 $!\n"
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//usage: "pid 4790's current affinity mask: 7\n"
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//usage: "pid 4790's new affinity mask: 1\n"
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//usage: "$ taskset 0x7 /bin/sh -c './taskset -p 0x1 $$'\n"
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//usage: "pid 6671's current affinity mask: 1\n"
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//usage: "pid 6671's new affinity mask: 1\n"
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//usage: "$ taskset -p 1\n"
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//usage: "pid 1's current affinity mask: 3\n"
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/*
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* Not yet implemented:
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* -a/--all-tasks (affect all threads)
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* needs to get TIDs from /proc/PID/task/ and use _them_ as "pid" in sched_setaffinity(pid)
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*/
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#include <sched.h>
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#include "libbb.h"
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typedef unsigned long ul;
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#define SZOF_UL (unsigned)(sizeof(ul))
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#define BITS_UL (unsigned)(sizeof(ul)*8)
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#define MASK_UL (unsigned)(sizeof(ul)*8 - 1)
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#if ENABLE_FEATURE_TASKSET_FANCY
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#define TASKSET_PRINTF_MASK "%s"
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/* craft a string from the mask */
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static char *from_mask(const ul *mask, unsigned sz_in_bytes)
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{
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char *str = xzalloc((sz_in_bytes+1) * 2); /* we will leak it */
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char *p = str;
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for (;;) {
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ul v = *mask++;
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if (SZOF_UL == 4)
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p += sprintf(p, "%08lx", v);
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if (SZOF_UL == 8)
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p += sprintf(p, "%016lx", v);
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if (SZOF_UL == 16)
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p += sprintf(p, "%032lx", v); /* :) */
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sz_in_bytes -= SZOF_UL;
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if ((int)sz_in_bytes <= 0)
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break;
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}
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while (str[0] == '0' && str[1])
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str++;
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return str;
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}
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#else
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#define TASKSET_PRINTF_MASK "%lx"
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static unsigned long from_mask(ul *mask, unsigned sz_in_bytes UNUSED_PARAM)
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{
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return *mask;
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}
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#endif
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static unsigned long *get_aff(int pid, unsigned *sz)
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{
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int r;
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unsigned long *mask = NULL;
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unsigned sz_in_bytes = *sz;
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for (;;) {
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mask = xrealloc(mask, sz_in_bytes);
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r = sched_getaffinity(pid, sz_in_bytes, (void*)mask);
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if (r == 0)
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break;
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sz_in_bytes *= 2;
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if (errno == EINVAL && (int)sz_in_bytes > 0)
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continue;
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bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
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}
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//bb_error_msg("get mask[0]:%lx sz_in_bytes:%d", mask[0], sz_in_bytes);
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*sz = sz_in_bytes;
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return mask;
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}
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#if ENABLE_FEATURE_TASKSET_CPULIST
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/*
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* Parse the CPU list and set the mask accordingly.
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*
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* The list element can be either a CPU index or a range of CPU indices.
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* Example: "1,3,5-7". Stride can be specified: "0-7:2" is "0,2,4,6".
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* Note: leading and trailing whitespace is not allowed.
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* util-linux 2.31 allows leading and sometimes trailing whitespace:
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* ok: taskset -c ' 1, 2'
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* ok: taskset -c ' 1 , 2'
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* ok: taskset -c ' 1-7: 2 ,8'
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* not ok: taskset -c ' 1 '
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* not ok: taskset -c ' 1-7: 2 '
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*/
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static void parse_cpulist(ul *mask, unsigned max, char *s)
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{
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char *aff = s;
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for (;;) {
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unsigned bit, end;
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unsigned stride = 1;
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bit = end = bb_strtou(s, &s, 10);
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if (*s == '-') {
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s++;
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end = bb_strtou(s, &s, 10);
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if (*s == ':') {
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s++;
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stride = bb_strtou(s, &s, 10);
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}
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}
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if ((*s != ',' && *s != '\0')
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|| bit > end
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|| end == UINT_MAX /* bb_strtou returns this on malformed / ERANGE numbers */
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|| (stride - 1) > (UINT_MAX / 4)
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/* disallow 0, malformed input, and too large stride prone to overflows */
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) {
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bb_error_msg_and_die("bad affinity '%s'", aff);
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}
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while (bit <= end && bit < max) {
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mask[bit / BITS_UL] |= (1UL << (bit & MASK_UL));
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bit += stride;
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}
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if (*s == '\0')
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break;
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s++;
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}
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}
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static void print_cpulist(const ul *mask, unsigned mask_size_in_bytes)
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{
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const ul *mask_end;
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const char *delim;
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unsigned pos;
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ul bit;
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mask_end = mask + mask_size_in_bytes / sizeof(mask[0]);
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delim = "";
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pos = 0;
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bit = 1;
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for (;;) {
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if (*mask & bit) {
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unsigned onebit = pos + 1;
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printf("%s%u", delim, pos);
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do {
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pos++;
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bit <<= 1;
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if (bit == 0) {
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mask++;
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if (mask >= mask_end)
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break;
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bit = 1;
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}
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} while (*mask & bit);
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if (onebit != pos)
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printf("-%u", pos - 1);
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delim = ",";
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}
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pos++;
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bit <<= 1;
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if (bit == 0) {
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mask++;
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if (mask >= mask_end)
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break;
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bit = 1;
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}
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}
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bb_putchar('\n');
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}
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#endif
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enum {
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OPT_p = 1 << 0,
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OPT_a = 1 << 1,
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OPT_c = (1 << 2) * ENABLE_FEATURE_TASKSET_CPULIST,
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};
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static int process_pid_str(const char *pid_str, unsigned opts, char *aff)
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{
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ul *mask;
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unsigned mask_size_in_bytes;
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const char *current_new;
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pid_t pid = !pid_str ? 0 : xatou_range(pid_str, 1, INT_MAX); /* disallow "0": "taskset -p 0" should fail */
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mask_size_in_bytes = SZOF_UL;
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current_new = "current";
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print_aff:
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mask = get_aff(pid, &mask_size_in_bytes);
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if (opts & OPT_p) {
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#if ENABLE_FEATURE_TASKSET_CPULIST
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if (opts & OPT_c) {
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printf("pid %d's %s affinity list: ", pid, current_new);
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print_cpulist(mask, mask_size_in_bytes);
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} else
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#endif
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printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
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pid, current_new, from_mask(mask, mask_size_in_bytes));
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if (!aff) {
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/* Either it was just "-p <pid>",
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* or it was "-p <aff> <pid>" and we came here
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* for the second time (see goto below) */
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return 0;
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}
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current_new = "new";
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}
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memset(mask, 0, mask_size_in_bytes);
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if (!ENABLE_FEATURE_TASKSET_FANCY) {
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/* Affinity was specified, translate it into mask */
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/* it is always in hex, skip "0x" if it exists */
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if (aff[0] == '0' && (aff[1]|0x20) == 'x')
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aff += 2;
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mask[0] = xstrtoul(aff, 16);
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}
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#if ENABLE_FEATURE_TASKSET_CPULIST
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else if (opts & OPT_c) {
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parse_cpulist(mask, mask_size_in_bytes * 8, aff);
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}
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#endif
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else {
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unsigned i;
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char *last_char;
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/* Affinity was specified, translate it into mask */
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/* it is always in hex, skip "0x" if it exists */
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if (aff[0] == '0' && (aff[1]|0x20) == 'x')
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aff += 2;
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i = 0; /* bit pos in mask[] */
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/* aff is ASCII hex string, accept very long masks in this form.
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* Process hex string AABBCCDD... to ulong mask[]
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* from the rightmost nibble, which is least-significant.
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* Bits not fitting into mask[] are ignored: (example: 1234
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* in 12340000000000000000000000000000000000000ff)
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*/
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last_char = strchrnul(aff, '\0');
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while (last_char > aff) {
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char c;
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ul val;
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last_char--;
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c = *last_char;
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if (isdigit(c))
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val = c - '0';
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else if ((c|0x20) >= 'a' && (c|0x20) <= 'f')
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val = (c|0x20) - ('a' - 10);
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else
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bb_error_msg_and_die("bad affinity '%s'", aff);
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if (i < mask_size_in_bytes * 8) {
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mask[i / BITS_UL] |= val << (i & MASK_UL);
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//bb_error_msg("bit %d set", i);
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}
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/* else:
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* We can error out here, but we don't.
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* For one, kernel itself ignores bits in mask[]
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* which do not map to any CPUs:
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* if mask[] has one 32-bit long element,
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* but you have only 8 CPUs, all bits beyond first 8
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* are ignored, silently.
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* No point in making bits past 31th to be errors.
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*/
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i += 4;
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}
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}
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/* Set pid's or our own (pid==0) affinity */
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if (sched_setaffinity(pid, mask_size_in_bytes, (void*)mask))
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bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid);
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//bb_error_msg("set mask[0]:%lx", mask[0]);
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if ((opts & OPT_p) && aff) { /* "-p <aff> <pid> [...ignored...]" */
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aff = NULL;
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goto print_aff; /* print new affinity and exit */
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}
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return 0;
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}
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static int FAST_FUNC iter(const char *dn UNUSED_PARAM, struct dirent *ent, void *aff)
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{
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if (isdigit(ent->d_name[0]))
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return process_pid_str(ent->d_name, option_mask32, aff);
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return 0;
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}
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int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int taskset_main(int argc UNUSED_PARAM, char **argv)
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{
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const char *pid_str;
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char *aff;
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unsigned opts;
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/* NB: we mimic util-linux's taskset: -p does not take
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* an argument, i.e., "-pN" is NOT valid, only "-p N"!
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* Indeed, util-linux-2.13-pre7 uses:
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* getopt_long(argc, argv, "+pchV", ...), not "...p:..." */
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opts = getopt32(argv, "^+" "pa"IF_FEATURE_TASKSET_CPULIST("c")
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"\0" "-1" /* at least 1 arg */);
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argv += optind;
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aff = *argv++;
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if (!(opts & OPT_p)) {
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/* <aff> <cmd...> */
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if (!*argv)
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bb_show_usage();
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process_pid_str(NULL, opts, aff);
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BB_EXECVP_or_die(argv);
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}
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pid_str = aff;
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if (*argv) /* "-p <aff> <pid> ...rest.is.ignored..." */
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pid_str = *argv;
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else
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aff = NULL;
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if (opts & OPT_a) {
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char *dn;
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int r;
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dn = xasprintf("/proc/%s/task", pid_str);
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r = iterate_on_dir(dn, iter, aff);
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IF_FEATURE_CLEAN_UP(free(dn);)
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if (r == 0)
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return r; /* EXIT_SUCCESS */
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/* else: no /proc/PID/task, act as if no -a was given */
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}
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return process_pid_str(pid_str, opts, aff);
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}
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